偏压对空心阴极放电等离子体溅射制备氮化碳薄膜的影响

利用空心阴极放电等离子体源在Si（100）单晶衬底上沉积了氮化碳薄膜．薄膜的表面形貌表明所得的薄膜非常的均匀光滑，用X光电子能谱、拉曼和红外吸收光谱对薄膜的结构、成分和化学键等进行了研究．在拉曼光谱中可以看到典型的G，D和C=N键的峰．当偏压为250V时．薄膜拉曼光谱中的D峰完全消失，此时薄膜的N／C比达到了0．81．通过对薄膜的XPS分析也表明薄膜中C—C，sp^2 CN和sp^3 CN键的组分也发生了明显的变化．当偏压为250V时薄膜的sp^3 CN相的含量达到了最大值为40％，同时氮含量也达到了最大值．实验结果给出了直接的证据：薄膜的结构模式可以通过改变偏压来得到控制．     

椭偏法表征四面体非晶碳薄膜的化学键结构

采用自主研制的双弯曲磁过滤阴极真空电弧(FCVA)技术,在不同衬底负偏压下制备了四面体非晶碳(ta-C)薄膜。通过分光光度计和椭偏(SE)联用技术精确测量了薄膜厚度,重点采用椭偏法对不同偏压下制备的ta-C薄膜sp3 C键和sp2 C键结构进行了拟合表征,并与X射线光电子能谱(XPS)和拉曼光谱的实验结果相对比,分析了非晶碳结构的椭偏拟合新方法可靠性。结果表明,在-100V偏压时薄膜厚度最小,为33.9nm;随着偏压的增加,薄膜中的sp2 C含量增加,sp3 C含量减小,光学带隙下降。对比结果发现,椭偏法作为一种无损、简易、快速的表征方法,可用于ta-C薄膜中sp2 C键和sp3 C键含量的准确测定,且在采用玻璃碳代表纯sp2 C的光学常数及拟合波长选取250～1700nm时的椭偏拟合条件下,拟合数值最佳。     

工作压强对硅掺杂辉光放电聚合物结构和性能的影响

采用辉光放电聚合技术,在不同工作压强条件下制备了掺硅的辉光放电聚合物(Si-GDP)薄膜.并采用傅里叶变换红外吸收光谱和X射线光电子能谱(XPS)对Si-GDP薄膜进行了表征,分析了压强变化对其内部结构及成分的影响.利用紫外—可见光谱对Si-GDP薄膜的光学带隙进行了分析.结果表明:Si-GDP薄膜中Si元素主要以Si—C,Si—H,Si—O,Si—CH₃的键合形式存在;随着工作压强的增大,薄膜中Si—C键相对含量先减小后增加;从Si-GDP薄膜的XPS分析可以发现,C—C与C C含 关键词： 硅掺杂辉光放电聚合物薄膜 工作压强 傅里叶变换红外吸收光谱 X射线光电子能谱     

含氮氟化类金刚石(FN-DLC)薄膜的研究:(Ⅰ)sp结构与化学键分析

以CF4,CH4和N2为源气体,利用射频等离子体增强化学气相沉积法,在不同功率下制备了含氮氟化类金刚石膜.用俄歇电子能谱、拉曼光谱、X射线光电子能谱和傅里叶变换红外光谱对薄膜的电子结构和化学键进行了表征,并结合高斯分峰拟合方法分析了薄膜中sp2,sp3结构比率.结果表明,制备的薄膜属于类金刚石结构,不同沉积功率下,薄膜内的sp2/sp3值在2.0—9.0之间,随着沉积功率的增加薄膜内sp2的相对含量增加.膜内主要有C—Fx(x=1,2),C—C,CC和CN等化学键.沉积功率增加,C—C基团增加,膜内F的浓度降低,C—F基团减少,薄膜的关联加强,稳定性提高.     

CN薄膜结构特性的研究

利用离化团束(ICB)方法在Si(111)衬底上生长了CN薄膜。X光衍射(XRD)分析表明薄膜呈β-C₃N₄晶态结构,X射线光电子能谱(XPS)测定薄膜含N量为20％,并且观察到C1_s和N1_s芯能级谱中存在双峰。红外吸收光谱呈现C—N和C≡N的吸收峰。高能反射式电子衍射(RHEED)也证实薄膜中存在晶态物质。薄膜的努氏显微硬度值达到6200kgf·mm^-2。 关键词：     

沉积参数对碳氮化硅薄膜化学结构及光学性能的影响

利用微波电子回旋共振（MW ECR）等离子体增强非平衡磁控溅射法制备了碳氮化硅（SiCN）薄膜。研究结果表明：硅靶溅射功率和氮气流量对薄膜化学结构、光学、力学等性能有很大影响。傅里叶变换红外光谱（FT IR）和X射线光电子能谱（XPS）表征显示，随着硅靶溅射功率由150W增加到350W，薄膜中C Si N键含量由14.3%增加到43.6％; 氮气流量的增大（2～15sccm）易于形成更多的sp2C＝N键和sp1C≡N键。在改变硅靶溅射功率和氮气流量的条件下，薄膜光学带隙最大值分别达到2.1eV和2.8eV。     

丙酮环境下ECR微波等离子体辅助化学气相沉积类金刚石薄膜研究

利用电子回旋共振（ECR）微波等离子体辅助化学气相沉积技术、工作气氛为丙酮，在光学玻璃衬底上得到了光滑、致密、均匀的类金刚石薄膜.在工艺研究中，对等离子体中氧的存在及其作用进行了分析.原子力显微镜分析表明，薄膜的表面粗糙度小于10nm，晶粒 尺寸约为100nm.拉曼光谱和中红吸收谱研究发现，薄膜具有强烈的荧光效应，含有sp1，sp2，sp3杂化C—C，sp3杂化CH3，羰基CO、含氧多元 环以及—COOH基等.利用纳米力学探针以 及近红区红外透射谱分析了薄膜的力学及光学性能，结果表明，薄膜的显微硬度接近4 关键词： 类金刚石薄膜 ECR微波等离子体 丙酮气氛 红外光谱     

电解有机溶液法在Si表面制备类金刚石薄膜及退火对其结构的影响

在对不同有机溶剂分子结构分析的基础上,选取甲醇、DMF(N,N-二甲基甲酰胺)和乙腈溶液为碳源,以脉冲直流电源电解有机溶液的方法在Si片上制得了含氢类金刚石薄膜(DLC薄膜),并研究了退火对薄膜结构的影响.通过X射线光电子能谱(XPS),喇曼(Raman)和红外(IR)光谱对薄膜的结构进行了分析表征.XPS表明薄膜的主要成分为C,喇曼光谱显示所得薄膜为典型DLC薄膜.喇曼和红外光谱还表明,膜中含有大量H并且主要键合于sp³碳处.随着退火的进行薄膜中的H被去除.随温度升高薄膜电阻率的下 关键词： 类金刚石薄膜 退火     

a-C:H膜化学结构对光学性能的影响

选用体积分数为99.999 9%的H2及反式-2-丁烯(T2B)为工作气体,利用低压等离子体增强化学气相沉积法制备了a-C;H薄膜.利用傅里叶变换红外光谱仪和X射线光电子能谱对薄膜化学键和电子结构进行分析,并结合高斯分峰拟合分析了薄膜中sp3/sp2杂化键比值和sp3C杂化键分数.结果表明:薄膜中氢含量较高,主要以sp3C-H形式存在;工作气压越高,制备的薄膜中C=C键含量越少,薄膜中sp3/sp2杂化键比值和sp3C杂化键分数增加,薄膜稳定性提高.应用UV-VIS光谱仪,获得了波长在400～1 000 nm范围内薄膜的光吸收特性,结果显示:a-C:H薄膜透过率可达98%.光学常数公式计算得到工作压强为4～14 Pa时光学带隙在2.66～2.76之间,并均随着工作气压的升高而增大.结果表明,随工作气压的升高,薄膜内sp3键减小,从而促使透过率、光学带隙增大.     

高温处理对CNx薄膜晶化的影响

利用直流磁控溅射制得非晶态氮化碳膜,然后在高温下、常压N气氛中进行热处理,利用DTA,XRD和Auger研究晶化前后氮化碳成分、结构以及键态的变化.实验结果表明:在1186℃附近出现了晶化现象,高温晶化处理可以促进无定形氮化碳向晶态转变,在XRD图谱上出现α-C3N4衍射峰.Auger实验结果表明膜中出现富C,Si,N的区域.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.     

Design optimization of highly sensitive LSPR enhanced surface plasmon resonance biosensors with nanoholes

For breaking through the sensitivity limitation of conventional surface plasmon resonance (SPR) biosensors, novel highly sensitive SPR biosensors with Au nanoparticles and nanogratings enhancement have been proposed recently.But in practice, these structures have obvious disadvantages.In this study, a nanohole based sensitivity enhancement SPR biosensor is proposed and the influence of different structural parameters on the performance is investigated by using rigorous coupled wave analysis (RCWA).Electromagnetic field distributions around the nanohole are also given out to directly explain the performance difference for various structural parameters.The results indicate that significant sensitivity increase is associated with localized surface plasmons (LSPs) excitation mediated by nanoholes.Except to outcome the weakness of other LSP based biosensors, larger resonance angle shift, reflectance amplitude, and sharper SPR curves' width are obtained simultaneously under optimized structural parameters.     

Polymer gratings based on photopolymerization for low-order distributed feedback polymer lasers

Novel polymer distributed feedback(DFB)gratings are fabricated based on photopolymerization to reduce lasing threshold of polymer lasers.A photopolymer formulation sensitive to 355-nm ultraviolet(UV)light is proposed for the fabrication of polymer gratings and it can be used to form polymer films by spin-coating process.A very low surface-relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive-index modulation of about 0.012.The experimental results indicate that such polymer gratings have promising potentials for the fabrication of low-order DFB organic semiconductor lasers.